Both were pleased with level-par 72s, efforts which left them sitting joint-24th on a day when three-time Senior major winner Colin Montgomerie had to settle for a 76 that included a visit to the Barry Burn at the last.
Oldcorn, who ended a five-year drought on the over-50s circuit with a victory in Germany, birdied the 16th, a 235-yard par 3, as he covered final four holes in one-under.
“I can’t recall making a birdie there before,” admitted the 56-year-old. “The hybrid I hit there to eight feet was a beauty - the best shot I hit all the day.”
Arnott, who came through a qualifier at Montrose on Monday to secure his debut in the event, would have been sitting a shot off the lead if he’d been able to buy the two pars that Oldcorn then finished with. Instead, the 32-year-old Bishopbriggs Golf Range professional let his three-under position slip by closing 6-5.
“I finished in an ambulance,” he joked afterwards, the double-bogey having resulted from him ending up with a difficult stance close to the burn and the bogey being caused by a penalty shot after finding water. He almost escaped with a par only to see an 18-foot putt hang on the lip of the hole.
“If you had offered me 72, I’d have taken it,” admitted Arnott, who hasn’t gone back to the European Senior Tour Qualifying School since earning an alternate card two years ago and hardly getting any starts. “I don’t see the point in spending £2,500, but I’ll see at the end of the year,” said the Tartan Tour stalwart about the possibility of giving it a crack again.